Intestinal Ischemia
Ashley Ciosek
Acute Mesenteric Ischemia
Presentation
- Early: Abdominal pain is most common symptom, abdominal distension (“pain out of proportion to exam”, meaning pain develops before abd tenderness)
- Late: As transmural bowel infarction develops, abdomen becomes distended, bowel sounds become absent, and peritoneal signs develop
- Arterial occlusion: Sudden onset, severe periumbilical pain, nausea and emesis
- Venous thrombosis: More insidious onset abdominal pain, waxing and waning
- Non-occlusive mesenteric ischemia: variable location and severity of abdominal pain; often overshadowed by a precipitating disorder
Pathophysiology
- Sudden onset ↓ or absence of blood flow to the small intestines
- Mesenteric arterial occlusion:
- Arterial embolism: Associated with cardiac arrhythmias (atrial fibrillation), valvular disease, endocarditis, ventricular aneurysm, aortic atherosclerosis, and aortic aneurysm
- Arterial thrombosis: Most commonly from atherosclerotic disease; can also be 2/2 abdominal trauma, infection, or dissection
- Venous thrombosis:
- Associated w/ hypercoagulable states, malignancy, prior abdominal surgery, abdominal mass à venous compression, intra-abdominal inflammatory processes
- Non-occlusive mesenteric ischemia:
- Intestinal hypoperfusion and vasoconstriction; associated with decreased cardiac output, sepsis, vasopressor use
Evaluation
- Type and Screen, Lactic acid, BMP, CBC
- Imaging: KUB: Normal in > 25% of cases
- Ileus w/ distended bowel loops, bowel wall thickening, ± pneumatosis intestinalis (bowel wall air)
- Free intraperitoneal air à immediate abdominal ex-lap
- CT Angiography: no oral contrast, obscures mesenteric vessels, ↓ bowel wall enhancement
- Focal or segmental bowel wall thickening, intestinal pneumatosis, portal vein gas, porto-mesenteric thrombosis, mesenteric arterial calcification, mesenteric artery occlusion
Management
- General: IVFs, NPO, hemodynamic monitoring and support (try to avoid vasoconstricting agents), anticoagulation, broad-spectrum antibiotics, pain control
- If develops peritonitis or evidence of perforation on CT à EGS consult for surgery
- Mesenteric arterial embolism: Embolectomy vs. local infusion of thrombolytic agent
- Mesenteric arterial thrombosis: Surgical revascularization vs. thrombolysis with endovascular angioplasty and stenting
- Venous thrombosis: Anticoagulation; possible thrombolysis if persistent symptoms
- Non-occlusive disease: Treat underlying cause, stop vasoconstriction meds, consider intra-arterial vasodilator infusion
Acute Mesenteric Ischemia | Ischemic Colitis |
|---|---|
| Abd pain early on, then abd tenderness later (“pain out of proportion”) | Abd tenderness > abd pain |
| Acute illness, afib, endocarditis | 90% patients are >60 y/o |
| BRBPR less common overall (>24 hrs after pain starts) | BRBPR onset < 24 hrs into pain episode |
| Dx: CT angio abd | Dx: colonoscopy |
Chronic Mesenteric Ischemia
Background
- ↓ blood flow to intestines, typically caused by atherosclerosis of mesenteric vessel; risk factors include smoking, diabetes, sedentary lifestyle, age
- Also known as intestinal angina
- High-grade mesenteric vascular stenoses in at least two major vessels (celiac, SMA, or IMA) must be established
Presentation
- Recurrent dull, crampy, postprandial (<60min to onset) abdominal pain
- Pts develop food aversion and often have associated weight loss
Evaluation
- CTA abdomen/pelvis is preferred (>90% sensitivity and specificity)
- Can also consider duplex U/S (NPV ~99%), though less helpful if large habitus or prior abd surgery
Management
- Conservative management if asymptomatic: smoking cessation and secondary prevention to limit progression of atherosclerotic disease
- Nutritional evaluation
- Revascularization (open vs. endovascular) is indicated if symptoms are present
- Mesenteric angioplasty and stenting is first-line therapy
- Open revascularization preferred in younger pts and those w/ re-stenosis
- Goal is to prevent future bowel infarction
Ischemic Colitis
Background
- Sudden, transient reduction in blood flow to colon
- Typically at “watershed” regions of colon, such as the splenic flexure and rectosigmoid junction
- Most often nonocclusive (95% of cases) and affects older adults
- Risk factors: ACS, hemodialysis, shock, aortoiliac instrumentation, cardiopulmonary bypass, extreme exercise (marathon running)
Presentation
- Rapid onset, mild cramping abdominal pain, associated with urge to defecate, hematochezia
- Hematochezia is more commonly indicative of colonic (rather than small bowel) ischemia
- Tenderness present (typically over left side)
Evaluation
- Lactic acid (nonspecific but elevated), LDH, CPK, CBC (leukocytosis), BMP (metabolic acidosis)
- KUB
- CT A/P with IV contrast (and oral contrast if patient can tolerate)
- Consider CTA A/P if suspicion for vascular occlusion
- Colonoscopy confirms diagnosis.
- Edematous, friable mucosa; erythema; and interspersed pale areas; bluish hemorrhagic nodules representing submucosal bleeding
- Segmental distribution, abrupt transition between injured and non-injured mucosa
Management
- General: IVFs, bowel rest, antibiotics (Zosyn vs. CTX/Flagyl)
Ischemic Colitis Management | ||
| Classification | Management | |
| Mild | No risk factors* | Supportive care and observation Antibiotics can be stopped if noulceration |
| Moderate | 1-3 risk factors | Same as mild ischemia if no vascular occlusion Systemic anticoagulation +/- vascular intervention if mesenteric occlusion |
| Severe | > 3 risk factors, peritoneal signs, pneumatosis, pneumoperitoneum, gangrene or pancolonic ischemia on colonoscopy | Consult EGS for abdominal exploration and segmental resection |
| *Risk factors: male, SBP <90, HR >100, WBC>15k, Hgb <12, Na <136, BUN >20, LDH >350, isolated right-sided colonic involvement, abdominal pain with rectal bleeding | ||